Recently, an increasing number of the high-integrating and speeding up of Large Scale Integrated (LSI) circuits is in demand. Thus, the design rules of semiconductor elements configuring the LSI circuits are increasingly miniaturized. Therefore, the number of capacitors used in Dynamic Random Access Memories (DRAMs) increased, and the high permittivity of a dielectric film used in the capacitors also increased.
As a high-permittivity dielectric film used in a capacitor of a DRAM, a zirconium oxide (ZrO2) film is being studied.
As a method of forming the zirconium oxide film, an Atomic Layer Deposition (ALD) process is used. In the ALD process, for example, tetrakis ethylmethylamino zirconium (TEMAZ) is used as feed gas (precursor), O3 gas is used as an oxidant, and the feed gas and the O3 gas are supplied alternately.
However, when separately applying the zirconium oxide film as a dielectric film of a DRAM capacitor, it is difficult to produce both high permittivity and a low leakage current that are necessary for the dielectric films of next generation DRAMs.
To achieve, in the related art, high permittivity and a low leakage current, a capacitor using a two-layer structure is used. Such capacitor includes a ZrO2 film and a metal oxide film (including Ti) such as a TiO2 film, as a dielectric film.
However, the ZrO2 film frequently causes the loss of oxygen. Therefore, even though using the dielectric film having the two-layer structure that includes the ZrO2 film and the metal oxide film (including Ti) such as the TiO2 film as in the above description, it is not easy to achieve the high permittivity and the low leakage current to a desired level.